Two aluminium spheres P and Q, of masses 0.50 kg and 1.0 kg respectively, are released at the same time from the same height.

Why do they have the same acceleration?

1 answer

both spheres are gravitationally attracted to the Earth

the force of attraction is proportional to the product of the mass of the sphere and the mass of the Earth
... so the larger sphere experiences twice the force of the smaller sphere

Newton's 2nd law states that the acceleration of an object is
... directly proportional to the net force
... and inversely proportional to the object's mass
... f = m a ... a = f / m

twice the force on the larger sphere with twice the mass
... means that the acceleration of the two spheres is the same